The invention relates to a process for coating a substrate preferably made of a plastic material, with aluminum, including a direct current source which is connected to an electrode disposed in a coating chamber which can be evacuated. The electrode is electrically connected to the target to be sputtered and the sputtered particles are deposited on the substrate while a process gas is present in the coating chamber.
In known processes an aluminum layer is directly sputtered onto the plastic substrate, e.g. polycarbonate, without an intermediate or adhesive layer.
This process has the disadvantage of limiting the adhesive strength of the aluminum to a great extent. It turned out that when the coated substrates are stored over a longer period of time the layer, for example, can corrode.